8 replies to this topic

[hudaman]

Hi. Thanks for reading. I have a 998 with a pieced together stage 1 kit. Rc40 stainless manifold, mid section and tail. The aluminum intake minifold, pipercross filter with a stub stack inside. Have upgraded to an electronic dizzy. New gold uprated coil. Welded in a air fuel ratio monitor too. That's it I think. So here is my issue; after replacing the valve seals and rebuilding the stock (as far as I know) hs4 carb (with AAC needle) it doesnt run well at all. I set the valave clearance to .012. I then set the ignituon timing to 30 degrees max at 4000 rpm. I ran the jet adjusted nut down to get 14.5 on the meter. So the idle mixture is spot on. BUT when running accelerating slow or fast in any gear or load condition it leans out. Usually off the meter. I researched and also tried AAA, AAU, AAV and AAM needles and the same problem. So with the AAV needle in there, I adjusted the nut down until the running was in the zone. But now the idle is rich off the meter. Been working this issue for 3 weekends off and on. Sure would be nice getting her back on the road.

Any ideas out there?

I just came across someone saying the float level could be off. Is that possible? Going to try that next I suppose. So frustrating.

Thanks,
Scott

[carbon]

Scott,

 

A few questions about your carb settings:

- When you rebuilt the HS4 did you fit new main jet and new AAC needle?

- Can you also measure how far the top of the main jet sits below the carb bridge?

- What grade of damper oil are you using?

- Was there any sign of wear in the throttle spindle?

 

And about ignition - was timing set with the vacuum advance disconnected?

 

Low float level typically causes engine to misfire when engine not fully warmed up, choke in, and going round sharp corners (fuel moving away from jet). But worth checking the float chamber vent is not blocked.

 

And wild card. Is this a mini saloon or estate/van?

[hudaman]

I useed the original AAC needle that was in the carb. Before my 'fixing it' it ran extremely rich but it was rich at idle and at speed. I didn't have the meter then, so I don't know how much.

Not sure on the measurement right now. But it's way down there. I did the 13 flats out in the beginning, but when it was in a decent A/F range at idle it was off the chart lean. Will pull the top off and check.

I tried ATF fluid and 3in1 oil in the chamber. I also tried none, that wasn't good at all. . Couldn't find 20weight oil at my local store.

Throttle spindle has a bit of play. I got replacement bearings in the kit but was afraid of doing the machine myself. I do have 3 other hs4 carbs in varying stages of used but still scared.

I set the ignition timing with it connected. 4000 rpm, set timing light to advance 30 degrees and set the timing to the zero mark. That said, I've set it 3 other ways over the past month. Strangely, the new dizzy gets seized up once the engine warms up fully.

And finally, its is a saloon.

[hudaman]

Solved. Well, I found a ignition timing guide that, after the engine is warm, to advance the timing until it rpm stops rising then reduce it 250rpm.

I did this with the vacuum attached. At that time, the AAV needle was in. It was still running a bit lean, but was revving up much smoother.

 

I then changed from the 3 in 1 oil, (supposed to be SAE 20) to 5W20 in the dash pot. No idea if this changed anything, but it was a change I did.

When I changed the oil, I changed from the AAV back to the AAM needle.

 

Started the engine and dialed in the idle speed and fuel mixture to as close to 14.7 as I could get. It fluctuated a lot for some reason.

 

Buttoned everything up and took a drive. Came back home thinking it was still a bit weak. Put my timing light to it and was at 40 degrees advanced.

I then added 2 more degrees and took a drive. Seems great. I may add another 2 degrees and see how that works, but have gone about 130 miles so far and its running well, idles smooth and starts as required.

The air fuel meter fluctuates between 13-16 depending on rpm and load. Smells a bit rich to me at times.

 

So, with a home made stage 1 kit consisting of RC40 LCB, center section and rear box, alloy intake manifold with piper cross filter and stub stack, on a 998, a HS4 carb needs a AAM needle with, in my case, 42 degrees of ignition advance.

Initial MPG seems to be in the 35 range, however, that's at 65-75 on the interstate. Shes at 4500 RPM at 75, I imagine, at say, 55 it would be MUCH better.

 

Getting (have been since I bought the car) high pitched whistle at 20-30% throttle, I assume its air passing the throttle spindle, but not sure.

So irritating on an hour commute.

 

-Scott

[ings]

The mini has this nice daspod pin to tune the carb. you should find the pin on the left side under the dashpodcap. If you press it an nothing happens your carb is well tuned.

If rpm drops or rise it needs adjustments. Most mechanics or mini owners dont know this important button.

[cal844]

The mini has this nice daspod pin to tune the carb. you should find the pin on the left side under the dashpodcap. If you press it an nothing happens your carb is well tuned.
If rpm drops or rise it needs adjustments. Most mechanics or mini owners dont know this important button.

Later minis don't have this...

[hudaman]

As I only bought the Mini about a year ago, I have no idea of its changes over the years.

I assume all stock before, well besides the RC40 rear box and the alloy intake and some sort of aftermarket aircleaner.

 

The HS4 carb didn't have the pin, but before I installed the air fuel ration monitor, I used the "raise the piston" method for checking mixture at idle.

 

This is my 3rd British car, Had a 92 or  93 1.3 injected model. It was an automatic and I didnt touch it as we bought it new.

It lasted about 2 years and we got rid of it, the upkeep in Japan was insanely expensive. My second was a 2004 TVR Speed 6.

That car was a handful, so fast and but a pain in the bum to work on.

 

My current Mini has a lot to do, but its fun to work on. I have a spare 1275 out of a 90's something and a 88 1275 out of an ERA.

Now that it running, I can get the 1275 in position to begin the rebuild. Cant wait for that extra 300cc's of power!!

 

Scott

[ings]

I love the minis bu if i would live in japan i would grab one of these old skylines...

[hudaman]

Price being no object, sure, but even the Skylines of my day, the mid/late 80's, called Neumans or the Takamen, are nearly $20,000.

The Mini was only $4K, and left hand drive.

 

Driving a right hand drive in the US would be easy enough providing you didn't do any toll way driving or parking garages.

In Japan, most tolls had a left hand drive lane or machine to allow you make payment from that side.

No such forward thinking in the US.

 

Scott